During knee replacement surgery tibial trials are used to assist a surgeon in preparing the tibial surface for implantation of the tibial portion of the artificial knee. A surgeon uses a tibial tray trial to determine the tibial implant size, to make the appropriate cuts and reams in the bone, and to ensure a proper alignment and tibial component thickness prior to implanting the tibial components.
Such a procedure typically entails making an initial tibial plateau cut on the proximal tibial portion of the knee; determining a preferred size tray trial (and ultimately tray implants); placing the selected tray trial over the tibial surface; performing a trial reduction to ensure proper tibial component thickness and alignment; attaching a punch guide to the tibial tray trial; and cutting or reaming the tibial bone through openings in the punch guide and tray trial to prepare it to receive a stem or keel of the tibial implant. During this procedure it is necessary to fix the tray trial to the tibia, at least before cutting or reaming the tibial bone through openings in the punch guide and tray trial.
Known tibial tray trials, as illustrated in FIG. 1, typically include a tibial alignment handle 10 is attached to the tibial tray trial 12 to properly locate the trial with respect to a prepared tibia 14. Pins 16 are then driven through holes in the tray trial to fix the tray trial to the tibia 14. At least three hands are require to fix tibial tray trial 12 to tibia 14: one hand holds the tray trial 12 in place using handle 10; a second holds a pin 16 in place; and a third hand drives pin 14 through tray trial 12 into tibia 14 to fix the tray trial 12 thereto.
One difficulty with the known method for fixing a tibial tray trial to a tibia is that, because it requires more than two hands, a surgeon cannot fix the tray trial without help. Another problem involves the pins themselves. Because the pins must be removed in order to remove the trial to place the permanent prosthesis, they typically include portions that extend above the tray trial to facilitate their removal. However, trialing sometimes involves, particularly when implanting a rotating platform knee tibial prosthesis, moving or rotating a trial insert with respect to the tibial tray trial. When the pins extend above the surface of the tibial tray trial, the pins can prevent relative movement between the tray trial and the trial insert. In addition, pins that are separate from the tray may become lost during surgery, cleaning, or transportation.